Process of treating complex ores.



No. 678,210. Patented July 9, Will. J. W. WORSEY. PROCESS OF TREATING COMPLEX ORES.

(Application filed Sept. 17, 1900.)

(No Model.)

UNITED STATES PATENT OFFICE.

JAMES WESTHEAD YVORSEY, OF ST. HELENS, ENGLAND, ASSIGNOR OE TWO- THIRDS TO JOSEPH HENRY LANCASl-IIRE, OF STREATHAM, ENGLAND.

PROCESS OF TREATING COMPLEX ORES.

' SPECIFICATION forming part of LettersPatent No. 678,210, dated July 9, 1901.

Application filed September 17, 1900. Serial No. 30,349. (No specimens.)

To all whom it may concern:

Be it known that I, JAMES WESTHEAD WORSEY, a subject of the Queen of Great Britain, residing at 137 Boundary road, St.

contain more or less sulfur, zine, lead, silver,

gold, copper, and other substances. Various processes, both humid and dry, have been proposed for treating this class of ores, none of which have, however, proved perfectly satisfactory in practice.

The improved process on which a patent is now sought is of that class in which the ores are treated partly by roasting and partly by liquids, and the difficulties hitherto experienced in carrying out .this method of operation are entirely obviated thereby.

This invention is carried into operation as follows: The ore is first calcined and excess of sulfur driven off thereby. The evolved sulfurous-acid gas is preferably utilized along with other gas produced at a later stage of the process for the production of the sulfuric acid requisite at a subsequent stage of treatment. It is important that a certain percentage of sulfur be left in the ore after calcinationnot less than eight per cent. nor more than sixteen per cent. One of the principal advantages of the calcination is that the ore is rendered more porous and suitable for the subsequent operations. After calcination the ore is finely comminuted, so as to pass through a screen of forty meshes to the inch. It is then carefully sampled and assayed to ascertain its composition, and especially the percentage of zinc it contains. From these data the quantity of sulfuric acid requisite can be calculated. The next step in the process consists in mixing the ore with about two per cent. of commercial sodium nitrate. The mixed charge (preferably about forty hundredweight) is then placed in a vessel of fireproof material not acted upon by the acid employed and is then treated with dilute sulfuric acid of about 1.450 specific gravity. It

is usually necessary to use about one part, by weight, of acid to two parts of ore. The mixture is then gradually heated to its boilingpoint with constant stirring. During the heating large quantities of gas and vapor are evolved, consisting, chiefly, of steam and sulfurous and nitrous acids, and the apparatus is so constructed that these fumes, along with those arising from calcination, can be collected and passed into an ordinary vitriol-chamber and convertedinto sulfu ric acid in the well-known manner. When the residuary charge has become plastic, it is transferred into a closed or muffle furnace, where it is further heated out of contact withthe fire until all the gaseous fumes have escaped, the roasting being assisted by frequent stirring. They charge is then withdrawn from the-.lfurnace and is ready for further treatment. In most cases the material in the muffle-furnace will contain ferrous salt in quantity. If'it is desired to oxidize this, a corresponding quantity, carefully calculated, of a mixture of finely-ground sodium nitrate or other suitable oxidizing material with quicklimemay be thrown equally over the charge and stirred into it and the whole carefully heated until the iron present is oxidized into the ferric state. The iron is thus renderedinsoluble. ized or otherwise) is then placed in a vessel provided with an agitator and with a steam pipe so arranged that the whole of the ore can be well agitated in the liquid provided. In this ves'selthe charge is treated with a large quantity of dilute solution of sodium sulfate and the whole is well agitated and boiled by meansxof steam at about thirty pounds pressure for twenty minutes or more, Whereby most of the sulfate of zinc and also any copper present as sulfate will be dissolved. The steam is then turned off and the insolu# ble matter allowed to settle to the bottom of the tank, when the clear 'solntion-rcan be drawn off and the zinc can be extracted from the solution either as sulfate, carbonate, or

The roasted material (oxidoxid (so as to suit the requirements of the case) by the well known methods in use. Copper whenever present is first precipitated in the usual manner by the use of scrap sheet zinc or galvanized iron.

My method of treating the clear solution of zinc sulfate from the agitator consists in allowing it to stand in a large cooler in order that any lead sulfate held in suspension may subside. If traces of any other metal (such as silver) be present, these can be dealt with in the cooler. Afterward any appreciable amount of copper may be thrown down in a separate vessel, and finally the zinc itself collected in other tanks by means of cream of lime carefully added until the whole of the zinc is precipitated. In this case all the iron present in the solution precipitates also and the mass is passed through a filter-press or otherlike means to remove the surplus water. The mixed precipitates are then placed in a small reverberatory furnace and heated to a dull-red heat in the presence of air until the iron is thoroughly oxidized, after which the heat must be quickly raised and an oxidizingflame maintained, so as to sublime the zinc in the form of oxid, which is collected in a chamber provided for the purpose, a draft or current of air being maintained by the chamher being connected with a tall chimney or with an exhaust-fan, so that the whole of the zinc oxid can be collected in the proper receptacle. The oxid will be found to be of very superior quality and quite free from iron, in fact almost chemically pure.

The residue from the zinc-volatilizing furnace can be added to the washed ore from the agitator and smelted in the ordinary way for lead and silver, &c., and treated by the well-known Pattinson or the Parkes process, and it is worthy of note that the residual slag will be much freer from lead and silver than is usually the case with slag in the ordinary manner. Very large quantities of refractory ores of this class exist which are too poor to pay for the whole of this treatment, as they contain only small portions of zinc, but are fairly rich in lead and silver. Such ores can be mixed with commercial iron sulfate crystals in the proportion of from thirty to sixty per cent. parts of iron sulfate for every one hundred parts of roasted ore and then be added to the residue from the agitator and smelted in the ordinary way or separately, if desired.

Apparatus suitable for the carrying out of the above-described process is illustrated in the accompanying drawings, in which-- Figure 1 shows an elevation of a pot and roaster; Fig. 2, a sectional elevation thereof, and Fig. 3 a plan view thereof. Fig. 4 shows a sectional view of the agitator.

The furnace comprises a roasting-bed 1, a pot 2, with furnace under it, and a fireplace 3 for supplying the requisite heat to the roaster. The apertures 4 are the usual holes for stirring the charge and charging and discharging the furnace. The pot is connected by the tube 5 with the condenser or other apparatus leading to the draft-flue. The part marked 6 in Fig. 2 is the return-fine of the furnace of the blind roaster. It may be observed that this apparatus is thoroughly well known and in constant use for similar chem ical operations and is merely illustrated by way of example. .The agitator, Fig. l, includes the special steam-valve,com prising the block A, with central pin for passing through an aperture in the perforated disk D, secured to the enlarged end B of the steampipe. As long as no suflicient pressure of steam exists inside this device the weight of the steam-pipe maintains the part B firmly pressed against the bottom of the vessel. As soon, however, as a sufficient pressure is introduced into the tube the steam forces its way down through the perforations in D and between the block A and partB and into the surrounding liquid, causing the pipe to rise slightly to allow of the escape of steam. By this means a constant and varying escape of steam is caused all around the part B and the contents of the vessel are thoroughly agitated and mixed thereby.

WVhat I claim is- 1. Process for the treatment of complex sulfid ores comprising first the reduction of the combined sulfur below fifteen per cent. by calcination, secondly finely powdering the calcined ore, thirdly adding sodium nitrate, fourthly boiling the mixed ore and nitrate in dilute sulfuric acid, fifthly roasting the semisolid mass in a closed furnace, sixthly dissolving out zinc copper and other soluble salts from the said mass by weak sodium-sulfate solution, seventhly removing any copper from the solution, eighthly precipitating the zinc and other metals from the solution and ninthly separating the zinc.

2. Process for the production of zinc oxid from complex sullid ores, comprising partial removal of the sulfur by calcination of the ore, mechanical disintegration of the ore, addition of sodium nitrate to the ore, formation of zinc sulfate by boiling the ore with dilute sulfuric acid, roasting the product in a closed furnace, lixiviation of the roasted product with weak sodium-sulfate solution, removal of copper where present from the sodium-sulfate solution, precipitation of the zinc from the said solution by means of lime and sublimation of the zinc in an oxidizing atmosphere.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

JAMES VVESTHEAD \VORSEY.

Witnesses:

JOSEPH HENRY Lanoltsnmn, HERBERT SEFTON JONES. 

